High-breakdown-voltage semiconductor apparatus

Abstract

A high-breakdown-voltage semiconductor apparatus is provided, wherein when a gate capacitance of that portion of a gate electrode, under which a channel is formed, is Cg [F], a resistance in a channel length direction of that portion of the gate electrode, under which the channel is formed, is Rg [Ω], a threshold voltage, which is to be applied to the gate electrode and application of which permits flow of a drain current, is Vth [V], a voltage to be applied to the gate electrode to cut off the drain current is Voff [V], and a ratio of increase in the drain voltage per unit time at the time of cutting off the drain current is dV/dt [V/s], the following condition is satisfied: |Vth-Voff|≧0.5·Cg·Rg·(d V/dt)

We claim: 
     
       1. A high-breakdown-voltage semiconductor apparatus comprising: a first-conductity-type base layer;   a second-conductivity-type base layer formed on a surface of the first-conductivity-type base layer;   a first-conductivity-type source layer formed on a surface of the second-conductivity-type base layer;   a gate electrode provided over that portion of the second-conductivity-type base layer, which is interposed between the first-conductivity-type source layer and the first-conductivity-type base layer, with a gate insulation film interposed between the gate electrode and the interposed portion of the second-conductivity-type base layer;   a second-conductivity-type drain layer formed on a surface of the first-conductivity-type base layer, which is opposed to the surface thereof on which the second-conductivity-type base layer;   a drain electrode put in contact with the second-conductivity-type drain layer; and   a source electrode put in contact with the first-conductivity-type source layer and the second-conductivity-type base layer,   wherein when a gate capacitance of that portion of the gate electrode, under which a channel is formed, is Cg [F],   a resistance in a channel length direction of that portion of the gate electrode, under which the channel is formed, is Rg [Ω],   a threshold voltage, which is to be applied to the gate electrode and application of which permits flow of a drain current, is Vth [V],   a voltage to be applied to the gate electrode to cut off the drain current is Voff [V], and   a ratio of increase in the drain voltage per unit time at the time of cutting off the drain current is dV/dt [V/s],   the following condition is satisfied:   |Vth-Voff|≧0.5·Cg·Rg·(dV/dt)       
     
     
       2. The high-breakdown-voltage semiconductor apparatus according to claim 1, wherein a width of that portion of the gate electrode, at which the gate electrode is connected to gate electrode wiring, is greater than a width of the gate electrode. 
     
     
       3. The high-breakdown-voltage semiconductor apparatus according to claim 1, further comprising a second gate electrode formed on the gate electrode. 
     
     
       4. The high-breakdown-voltage semiconductor apparatus according to claim 3, wherein the gate electrode and the second gate electrode are covered with insulation films. 
     
     
       5. The high-breakdown-voltage semiconductor apparatus according to claim 3, wherein the source electrode is not provided on the second gate electrode. 
     
     
       6. The high-breakdown-voltage semiconductor apparatus according to claim 1, further comprising a first-conductivity-type emitter layer formed on the first-conductivity-type base layer and having an impurity dosage of 1×10 13  [cm -3  ] or less and a peak concentration of 1×10 15  [cm -3  ] or more and 1×10 16  [cm -3  ] or less. 
     
     
       7. The high-breakdown-voltage semiconductor apparatus according to claim 1, wherein a thickness of that portion of the gate insulation film, which is formed below a central portion of the gate electrode, is different from a thickness of that portion of the gate insulation film formed below an end portion of the gate electrode. 
     
     
       8. The high-breakdown-voltage semiconductor apparatus according to claim 1, further comprising a resistor connected between the gate electrode and a gate power supply. 
     
     
       9. The high-breakdown-voltage semiconductor apparatus according to claim 1, wherein when a width of the gate electrode is L G , a depth of the first-conductivity-type base layer is D B , a thickness of the second-conductivity-type base layer is W B , and a distance between the gate electrodes is L S , the following condition is satisfied:   60 μm≦L.sub.G, 5≦L.sub.G /L.sub.S, and 1≦L.sub.G.sup.2 /(D.sub.B ·W.sub.B)≦9     10.   
     
     
       10. A high-breakdown-voltage semiconductor apparatus comprising: a first-conductity-type base layer;   a second-conductivity-type base layer formed on a surface of the first-conductivity-type base layer;   a first-conductivity-type source layer formed on a surface of the second-conductivity-type base layer;   a gate electrode provided over that portion of the second-conductivity-type base layer, which is interposed between the first-conductivity-type source layer and the first-conductivity-type base layer, with a gate insulation film interposed between the gate electrode and the interposed portion of the second-conductivity-type base layer;   a second-conductivity-type drain layer formed on a surface of the first-conductivity-type base layer, which is opposed to the surface thereof on which the second-conductivity-type base layer;   a drain electrode put in contact with the second-conductivity-type drain layer; and   a source electrode put in contact with the first-conductivity-type source layer and the second-conductivity-type base layer,   wherein when a gate capacitance of that portion of the gate electrode, under which a channel is formed, is Cg [F],   a resistance in a channel length direction of that portion of the gate electrode, under which the channel is formed, is Rg [Ω],   a threshold voltage, which is to be applied to the gate electrode and application of which permits flow of a drain current, is Vth [V],   a voltage to be applied to the gate electrode to cut off the drain current is Voff [V], and   a ratio of increase in the drain voltage per unit time at the time of cutting off the drain current is dV/dt [V/s],   the following condition is satisfied:   |Vth-Voff|≧0.5·Cg·Rg·(dV/dt)        and wherein the first-conductivity-type base layer is subjected to a local lifetime control process.   
     
     
       11. A method of a driving high high-breakdown-voltage semiconductor apparatuses, wherein each of the high high-breakdown-voltage semiconductor apparatuses comprises: a first-conductity-type base layer;   a second-conductivity-type base layer formed on a surface of the first-conductivity-type base layer;   a first-conductivity-type source layer formed on a surface of the second-conductivity-type base layer;   a gate electrode provided over that portion of the second-conductivity-type base layer, which is interposed between the first-conductivity-type source layer and the first-conductivity-type base layer, with a gate insulation film interposed between the gate electrode and the interposed portion of the second-conductivity-type base layer;   a second-conductivity-type drain layer formed on a surface of the first-conductivity-type base layer, which is opposed to the surface thereof on which the second-conductivity-type base layer;   a drain electrode formed on the second-conductivity-type drain layer; and   a source electrode put in contact with the first-conductivity-type source layer and the second-conductivity-type base layer,   wherein when a gate capacitance of that portion of the gate electrode, under which a channel is formed, is Cg [F],   a resistance in a channel length direction of that portion of the gate electrode, under which the channel is formed, is Rg [Ω],   a threshold voltage, which is to be applied to the gate electrode and application of which permits flow of a drain current, is Vth [V],   a voltage to be applied to the gate electrode to cut off the drain current is Voff [V], and   a ratio of increase in the drain voltage per unit time at the time of cutting off the drain current is dV/dt [V/s],   the following condition is satisfied:   |Vth-Voff|≧0.5·Cg·Rg·(dV/dt)        and wherein the method of driving the high-breakdown-voltage semiconductor apparatuses comprises the steps of:   applying a first voltage to at least one of gates of the high-breakdown-voltage semiconductor apparatus, which is lower than a gate voltage at turn-on time, and   applying a second voltage for turning off to the at least one of the gates, which is lower than the first voltage.   
     
     
       12. The method of driving the high-breakdown-voltage semiconductor apparatus according to claim 11, further comprising the steps of: applying a third voltage to the at least one of the gates, which is lower than the first voltage, after the application of the first voltage.